Transform Coefficient Sign Prediction for Lower-Bitrate Video Coding
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Solution Overview
Problem
Existing video coding technologies face challenges in efficiently compressing video data while maintaining video quality due to limitations in bandwidth and memory resources, particularly in the context of transform coefficient sign prediction.
Innovation Solution
Implementations provide methods and apparatus for sign prediction of transform coefficients in video decoding and encoding, utilizing entropy encoding contexts to improve the accuracy of sign prediction and reduce bit rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional sign prediction methods are used for transform coefficients, then the encoding process is simpler, but the prediction accuracy is lower and bit rate is higher
Solution Approach 1:
The patent applies preliminary action by generating predicted signs for transform coefficients before the actual encoding process. The decoder generates predicted signs based on neighboring coefficients and entropy decodes correction information in advance, allowing the encoding system to prepare prediction data before final compression, thereby improving prediction accuracy without proportionally increasing complexity.
Solution Approach 2:
The patent implements feedback mechanisms where the encoder and decoder use entropy-coded correction information to refine predicted signs. The system continuously improves prediction accuracy by comparing predicted values with actual values and using the difference information (feedback) to adjust subsequent predictions, resolving the contradiction between accuracy and complexity.
2Measurement precision
If more bits are allocated for sign prediction, then prediction accuracy improves, but bit rate increases
Solution Approach 1:
The patent extracts only the essential correction information needed for sign prediction rather than encoding complete sign data. By separating the prediction process from the correction process and only transmitting the difference (correction) information through entropy coding, the system achieves high prediction accuracy while minimizing bit rate increase.
Solution Approach 2:
The patent changes the parameter representation from direct sign encoding to predictive correction encoding. Instead of allocating bits for every sign value, the system transforms the approach to encode only correction values with variable bit lengths based on entropy modeling, thereby reducing overall bit rate while maintaining or improving prediction accuracy.
3Productivity
If video compression is increased to reduce bandwidth usage, then transmission efficiency improves, but video quality degrades
Solution Approach 1:
The patent introduces sign prediction as an intermediary mechanism between the transform coefficients and the final compressed video. This intermediary process recovers sign information that would otherwise be lost during compression, acting as a bridge that maintains video quality while allowing higher compression ratios. The predicted signs serve as intermediate data that reconstructs lost information without requiring additional transmission bandwidth.
Data Source
AI summary
Implementations of the disclosure provide a video decoding apparatus and method for transform coefficient sign prediction on a video decoder side. The method may include receiving a bitstream including a sequence of sign signaling bits for a set of candidate transform coefficients. The method may further include generating a set of predicted signs for the set of candidate transform coefficients associated with a transform block of a video frame from a video. The method may also include decoding the sequence of sign signaling bits based on one or more contexts used to entropy-encode the sequence of sign signaling bits to obtain an indication of correctness of the predicted signs of the respective candidate transform coefficients. The method may additionally include estimating original signs for the set of candidate transform coefficients based on the set of predicted signs and the decoded sequence of sign signaling bits.